The role of memory in human strategy updating in optional public goods game.

Most research suggests that humans can optimize their behavior by imitating other humans. However, it remains unclear whether humans actually imitate others in real-life situations. To address this question, we conducted spatial public goods experiments with voluntary participation. In direct contrast to the prevailing view, the results of our experiments show that imitation plays an insignificant role in the decision making process. Furthermore, we found that the nature of human decision making relied more on their performances in the game's earlier history rather than the performance they observed in others. The action that gained better results in one's own history had a higher chance to be adopted even if this action did not work for the others.

Bounded rationality in volunteering public goods games.

It is one of the fundamental problems in biology and social sciences how to maintain high levels of cooperation among selfish individuals. Theorists present an effective mechanism promoting cooperation by allowing for voluntary participation in public goods games. But Nash's theory predicts that no one can do better or worse than loners (players unwilling to join the public goods game) in the long run, and that the frequency of participants is independent of loners' payoff. In this paper, we introduce a degree of rationality and investigate the model by means of an approximate best response dynamics. Our research shows that the payoffs of the loners have a significant effect in anonymous voluntary public goods games by this introduction and that the dynamics will drive the system to a fixed point, which is different from the Nash equilibrium. In addition, we also qualitatively explain the existing experimental results.

Evolutionary prisoner's dilemma on evolving random networks.

In this paper, we investigate the evolution of cooperation in the spatial prisoner's dilemma game by incorporating partner choice into the framework of evolutionary game theory. Our research shows that the introduction of partner choice can notably promote the cooperative behavior in the prisoner's dilemma game. All the players are more likely to play the game with cooperators, which makes it easier for cooperators to form alliances. In particular, the system will be dominated completely by cooperators in a comfortable environment (i.e., with lower survival cost) because the cooperators can get more benefits than the defectors in this case due to their good reputation. In addition, we have found that the sustenance of cooperators improves notably as well in the snowdrift game and the stag-hunt game due to this introduction.

Survival via cooperation in the prisoner's dilemma game.

By incorporating ecological dynamics into evolutionary games, we introduce natural and unnatural death to the spatial prisoner's dilemma game in which individuals can play mixed strategies. This introduction can give a simple explanation for the emergence and abundance of cooperation in animal and human societies. We found that individuals are more likely to cooperate in a highly competitive environment. In addition, our simulation results suggest that the individuals would tend to cooperate when the temptation to defect is small.

Bounded rationality leads to equilibrium of public goods games.

In this work, we introduce a degree of rationality to the public goods games in which players can determine whether or not to participate, and with it a new mechanism has been established. Existence of the bounded rationality would lead to a new equilibrium which differs from the Nash equilibrium and qualitatively explains the fundamental role of loners' payoff for maintaining cooperation. Meanwhile, it is shown how the potential strategy influences the players' decision. Finally, we explicitly demonstrate a rock-scissors-paper dynamics which is a consequence of this model.